A suicide bomber killed 14 people, most of them French naval engineers, with a devastating explosion outside a Karachi hotel yesterday.

The blast, which opened a crater in the road in front of the Sheraton hotel, was the latest in a series of attacks on westerners in Pakistan since September 11.

The 11 dead Frenchmen were working on a submarine project for the Pakistani navy.

The police said Islamic militants, possibly linked to al-Qaida, might be to blame.

Witnesses said a bus turned into the short drive in front of the hotel at 8am, as it had done every day for several months, to collect the engineers. A group of Frenchmen stood waiting to board.

Moments later an old Toyota car followed the bus up the drive and stopped a few metres away. The driver immediately detonated the explosives, reducing the 45-seat bus to a smoking wreck and shattering windows in the hotel and nearby buildings. In the front seat of the Toyota lay the charred remains of the bomber.

In France President Jacques Chirac condemned the attack as "vile" and "cowardly" and immediately sent his new defence minister, Michèle Alliot-Marie, to Karachi. All French engineers have been ordered home.

Mr Chirac told reporters: "French citizens performing their cooperation work in Karachi in Pakistan were victims of a murderous, cowardly, odious terrorist attack."

Last night 12 French citizens were in hospital under heavy armed security. Some were apparently only slightly injured. The French government sent a specially equipped plane to Karachi to bring them home.

French secret service agents were sent to Pakistan to investigate what appeared to be a serious breakdown in security before the suicide attack.

As well as the French victims, at least 11 Pakistanis were recovering in other hospitals. One of the injured, Iqbal, 51, a lorry driver, said he had stopped at a pharmacy opposite the Sheraton to buy medicine moments before the explosion.

"I had parked my truck and I was waiting at the window of the shop. I could see five foreigners standing at the entrance to the hotel. I saw the bus arrive and a car followed it into the driveway," he said.

"That was the last thing I remember. Then there was a huge bang. I was thrown up into the air. Pieces of glass from the pharmacy window cut into my body. I lay on the ground until my eyes cleared and then I ran to find help."

He suffered serious burns on his head and face. Shards of glass cut into his stomach, arms and his leg.

In another ward Lal Zada, 17, was recovering from serious glass cuts to his neck, hands and body. He had just stepped off a minibus in the main road outside the hotel and was walking towards a nearby tea stall where he worked when the bomb exploded.

"Suddenly there was a huge explosion and clouds of thick smoke everywhere," he said. "I felt the pain of pieces of glass cutting into my body."

A number of players from the New Zealand and Pakistani cricket teams were staying at a hotel across the road and were about to leave for a Test match.

None of the players was injured but the tour was immediately cancelled.

"People were screaming in the hotel and I saw a number of dead people lying on the road. It was horrific," said Waqar Younis, the Pakistan captain.

A British diplomat staying at the Sheraton was unhurt.

The engineers were working for the French state-owned marine company Direction de la Construction Navale on a project to build an Agosta 90B attack submarine, part of a big naval defence technology transfer project.

The deal, which involves three submarines, has become controversial because of allegations of serious corruption. At least one Pakistani naval officer was convicted of receiving kickbacks when the deal was signed in the mid-1990s.

After the September 11 attacks on the US, 80 French dockyard workers were flown back to Cherbourg because of a terrorist threat, but 40 were sent back earlier this year.

A secret service source in Paris said the posting was considered risky. The men had been told not to group together and the bus which took them to the Karachi dockyards was supposed to change its schedules and its route every day. On previous assignments the team frequently changed hotels.

"We will have to find out why the terrorist knew that the men would be leaving the Sheraton hotel at the time and why they were not taken to the dockyards in separate vehicles," the source said.

"This appears to have been a suicide bombing but the driver of the vehicle which exploded beside the bus must have been well informed about the routine.

"We will have to find out whether security measures were downgraded in the past few days.

"Obviously no one can rule out a possible connection with al-Qaida network, particularly as France is involved in military operations in Afghanistan."

The suicide attack is likely to deepen concern that Islamic militants in Pakistan are involved in a campaign against westerners in retaliation for the US bombing campaign in Afghanistan.

An American journalist, Daniel Pearl, was kidnapped and murdered in Karachi in January.

In March five people, including a US diplomat and her daughter, were killed in a suicide bombing at an Islamabad church.

Yesterday Pakistan's military ruler, General Pervez Musharraf, promised again to act against militancy.

"We feel this act of international terrorism has to be met with full force. My government has the complete resolve of meeting this threat," he said.

Although hundreds of militants have been arrested since a new crackdown began in January, most have been released, prompting concern about the general's commitment to breaking the military's deep links with militancy.

The wave of attacks on foreigners in Pakistan is already beginning to isolate the country. The US embassy has ordered home all families and non-essential staff.

Singapore Airlines, one of the few international airlines still flying to Pakistan, said it would suspend all flights from tomorrow. Future cricket tours are also in doubt.